1. Field of the Invention
The invention relates to a liquid crystal display; in particular, to a driving apparatus, a driving apparatus operating method, and a self-judgment slew rate enhancing amplifier applied in the liquid crystal display.
2. Description of the Related Art
In recent years, with the development of display technology, various novel types of display apparatus having different functions and advantages are shown in the market to replace the conventional cathode ray tube (CRT) monitor. Among them, the liquid crystal display (LCD) having advantages of saving power and small size is very popular and becomes a mainstream of the display market.
In general, the driving circuit in the LCD includes a timing controller (TCON), a source driver, and a gate driver. The timing controller is a control IC used for generating and outputting a control timing to control the timings of the source driver and the gate driver of the LCD panel.
Please refer to FIG. 1. FIG. 1 shows a conventional source driver. As shown in FIG. 1, the source driver 1 includes first latches 10a and 10b, second latches 12a and 12b, level shifters 14a and 14b, a N-type digital-analog converter 16a, a P-type digital-analog converter 16b, an exchanging switch 18, output buffers 19a and 19b, and output pads 20a and 20b. After a timing controller (not shown in FIG. 1) transmits digital input data to the source driver 1, the digital input data will be orderly stored in the first latches 10a and 10b corresponding to the first channel and the second channel respectively. When a STB signal is received, the digital input data will be stored in the second latches 12a and 12b respectively. Then, the digital input data with low level will be converted into the digital input data with high level by the level shifters 14a and 14b respectively, and then converted into analog input data by the N-type digital-analog converter 16a and the P-type digital-analog converter 16b respectively. Then, the exchanging switch 18 will selectively transmit the analog voltage to the output buffer 19a and 19b respectively and output the analog voltage to a display panel (not shown in FIG. 1) through the output pads 20a and 20b respectively to drive pixels on the display panel.
It should be noticed that the slew rate is defined as the rising or the falling of voltage in 1 msec. As to square wave, the conversion time needed for the output voltage to rise from wave trough to wave crest or fall from wave crest to wave trough is determined by the output current and the conversion voltage of the output voltage between the wave crest and wave trough. Every time when the digital input data that the timing controller inputs into the source driver 1 is changed, the analog voltage that the source driver 1 outputs to the display panel will be changed correspondingly. Different output voltage differences will make the output converting time also different. This will result in different voltage converting rates and affect the charging/discharging time of the panel pixels and limit its reaction time, so that the display quality of the display panel will be seriously damaged. Therefore, the above-mentioned problems occurred in the prior arts should be solved.